Fuel injection

ABSTRACT

The present invention relates to a fuel injection system for internal combustion engines. The system comprises at least one electromagnetically operated fuel injector for the injection of fuel into the induction pipe or manifold of the engine and means to provide a supply of exhaust gas from the engine to assist in atomization of the fuel. The flow of the exhaust gas is caused by the pressure differential between the exhaust gas pressure and the depression in the induction pipe or manifold. The fuel pressure to the injectors is adjusted as a function of the pressure of the exhaust gas to provide compensation for variations in fuel flow arising from changes in the pressure of the exhaust gas supply.

ties Patent [72] Inventors Albert E. lBaxendale Coventry; Brian ll. Croft, Coventry; George E. Fowle, Nuneaton, all of England [21] Appl. No. 835,620 [22] Filed June 23, 1969 [45] Patented Sept. 28, 19711 [73] Assignee Brico Engineering Limited Coventry, England [32] Priority July 4, 1968 [33] Great Britain [31] 32060/68 [54] FUEL INJECTION 1 Claim, 9 Drawing Figs.

[52] 11.5. Cl 1123/1119 A, 123/35, 123/52, 123/133, 123/139 [51] 1111. C1 ..lF02m 25/66 [50] Field otsenrcli 123/1 19 A, 119,119 B, 119 D, 139.17, 139.18, 52 M, 52 MV, 124,127, 35,133

[56] References Cited UNITED STATES PATENTS 2,511,213 6/1950 Leslie ..l23/l39.18UX

W m 15 n Primary Examiner-Wendell E. Burns Art0rneyl-lo1combe, Wetherill & Brisebois ABT1RACT: The present invention relates to a fuel injection system for internal combustion engines. The system comprises at least one electromagnetically operated fuel injector for the injection of fuel into the induction pipe or manifold of the engine and means to provide a supply of exhaust gas from the engine to assist in atomization of the fuel. The flow of the exhaust gas is caused by the pressure differential between the exhaust gas pressure and the depression in the induction pipe or manifold. The fuel pressure to the injectors is adjusted as a function of the pressure of the exhaust gas to provide compen sation for variations in fuel flow arising from changes in the pressure of the exhaust gas supply.

PATENTED was 197: 3508.531

SHEET- 2 OF 2 FUEL INJECTION This invention relates to fuel injection systems.

The invention provides a fuel injection system for an internal combustion engine comprising an electromagnetically operated fuel injector for the injection of fuel into the induction pipe or manifold of the engine, and means to provide a supply of exhaust gas from the engine to assist in atomization of said fuel, the flow of said exhaust gas being caused by the pressure difference between the exhaust gas pressure and the depression in the pipe or manifold.

One problem, which is encountered at present in the design of fuel metering systems for internal combustion engines of motor vehicles, is to ensure that the composition of the exhaust gas does not produce unacceptable atmospheric pollution.

It has been possible to design fuel metering systems which give acceptable levels of unbumt hydrocarbons and of carbon monoxide in the exhaust gas, without the necessity to resort to catalytic or combustion processes in the exhaust system. 7

However such fuel metering systems tend to operate successfully by metering a fuel quantity which gives a weak fuel/air ratio, and this in turn may result in the emission of an unacceptable quantity of the oxides of nitrogen in the exhaust gas.

We have found that the level of the oxides of nitrogen emitted may be reduced to an acceptable value by feeding an inert gas, namely engine exhaust gas into the engine cylinders.

The invention therefore also provides, an internal combustion engine having means for feeding an inert gas, namely engine exhaust gas into the engine cylinders.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. I shows, somewhat diagrammatically, a part of one embodiment of fuel injection system in accordance with the invention,

FIGS. 2 to 5 show respectively different modifications to the system of FIG. 1,

FIG. 6 illustrates a fuel supply arrangement to a plurality of fuel injectors; and

FIGS. 7 to 9, shows partly in section, views of three embodiments of fuel injector.

Referring to FIG. 1, there is shown diagrammatically the cylinder head 10 of an internal combustion engine, formed with an induction tract 11, an inlet valve 12 to a cylinder 9,

and an inlet manifold 13, in well-known fashion. It will be understood that generally the engine will have a plurality of cylinders, e.g. four or six, each with its own inlet valve.

An electromagnetically operated fuel injector 8, of which there may be one provided for each cylinder, located in the region of the inlet valve 12, is formed with an outer sleeve 15, which is attached to the inlet manifold 13, from which sleeve the fuel injector body 16 is supported so that an annular passage 17 is formed around the body. The fuel injector may, for example, be basically constructed as described in U.S. Pat. No. 3,247,833, and supplied with fuel through a fuel passage 18.

A supply of inert gas, namely exhaust gas, is led from the exhaust system of the engine (not shown) through passage 19 to the annular passage 17. The fuel injector body 16 has a fuel nozzle 20 which is coaxial with an atomizing nozzle 21 formed in the inner end wall of the sleeve 15, the atomizing nozzle being large enough to allow the nonatomized jet of fuel to enter it, but sufficiently small that the exhaust gas drawn through it from annular passage 17 causes atomization of the fuel, while allowing the engine to idle at a slow speed. It will be seen that the flow of exhaust gas is caused by the difference between the pressure of the exhaust gas at the upstream end of passage I9 and the depression in the inlet manifold 13. By injecting inert exhaust gas as just described, the control of exhaust emission is improved and atmospheric pollution, particularly by the oxides of nitrogen, is reduced to an acceptable value. The exhaust gas serves both to assist in atomization of the fuel from the nozzle 20, and also to reduce to an acceptathe engine, since the exhaust gas passing through the atomizing nozzle 21 is inspired into the cylinder through the induction tract 11.

Referring now to FIG. 2, there is shown a modification in which, instead of a plane wall closing off the inner end of sleeve 15, the wall 22 is inwardly-curved, in semitoroidal form, resulting in local reversal of the direction of exhaust gas flow.

In the modification shown in FIG. 3, instead of a plane wall, the inner end of sleeve 15 has a conical tapered part 32, followed by a cylindrical part 33, to give a funnel shape resulting in acceleration of the gas flow towards the atomizing nozzle 21.

In FIGS. 4 and 5 there are shown embodiments in which heat transfer is obtained from the hot exhaust gas to the fuel, so as to promote vaporization of the fuel. In FIG. 4, the passage 19 is connected to the downstream end of a sleeve 45, which, with an inner sleeve 46, forms an annular passage 47 through which the heated air or hot exhaust gas flows towards the fuel nozzle 20, where it reverses direction and mixes with the injected fuel, flowing out through an atomizing nozzle 4I formed in the end wall of inner sleeve 46.

The atomized fuel passes through the passage 48 within sleeve 46 and the heat exchange through the wall of sleeve 46 increases the vaporization.

In the embodiment of FIG. 5, the arrangement is similar to a that of FIG. 1, except that an extension'tube 55 projects from ble level the emission of oxides of nitrogen from the exhaust of 75 the end of sleeve 15, downstream of nozzle 21, to prolong the time during which the fuel is mixed with the heated exhaust gas, and thus to increase the amount of vaporization.

In FIG. 6 there is shown diagrammatically a'method of compensating for variations in fuel flow arising from changes in the pressure of the exhaust gas supply in the passage 19. Four fuel injectors 8 are shown which are fed withfuel under pressure from a tank 60, through pump 61 and fuel supply line 62. The pressure in the" supply line 62 is determined by the pressure control valve 63, and excess fuel is bypassed back to the tank through the return line 64. The desired compensation is achieved by subjecting the valve 63 to a reference pressure, which is the same as the pressure in line 65 causing the flow of exhaust gas through passage 19 and the atomizing nozzle. Thus, as the reference pressure in pipe line 65 decreases, tending to cause change in the rate of fuel delivery, the reference pressure acts on the valve 63 to alter the pressure of the fuel supply to the injectors, in such a way as to provide the desired compensation.

The fuel injection systems of the present invention may incorporate other features as described and claimed in US. Pat. No. 3,272,187.

FIGS. 7 to 9 show, partly in section, three embodiments of fuel injector for use in the system of the present invention. In each case, the injector is electromagnetically operated and is constructed generally in the manner described in US. Pat. No. 3,247,833. a

In the embodiment of FIG. 7, the injector is similar to that shown diagrammatically in FIG. 3 and corresponding parts bear the same numerals. Fuel is fed to the valve through the inlet l8and the energizing coil for the electromagnet is shown at 71. The inlet 18 is contained withing a housing 72 which, together with the sleeve or mixing chamber 15, surrounds the injector. The parts 72 and 15 are secured together and the latter serves to supportthe injector from the inlet manifold of the engine. The sleeve 15 has a conical tapered part 32 leading to the atomization nozzle 21.

The embodiment of FIG. 8 has an inwardly-curved wall portion 22 similar to that shown in FIG. 2; while the embodiment of FIG. 9 has an extension tube 55 similar to that shown in FIG. 5.

In each embodiment of injector, the fuel nozzle 20 may have a diameter of 0.020 inches and the atomizing nozzle 21 may have a diameter of 0.052 inches. Thus fuel issuing from the fuel nozzle is entrained in the exhaust gas stream to pass through the atomization nozzle.

We claim:

l. A fuel injection system for an internal combustion engine, including a plurality of electromagnetic-ally operated fuel injectors for the injection of fuel into the induction pipe or manifold of the engine and means to provide a supply of exhaust gas of the engine to assist in atomization of said fuel, the flow of said exhaust gas being caused by the pressure difference between the exhaust gas pressure and the depression in said induction pipe or manifold, the injectors being fed with fuel under pressure from a fuel supply through a common supply line and including a return line to the fuel supply fed LII 

1. A fuel injection system for an internal combustion engine, including a plurality of electromagnetically operated fuel injectors for the injection of fuel into the induction pipe or manifold of the engine and means to provide a supply of exhaust gas of the engine to assist in atomization of said fuel, the flow of said exhaust gas being caused by the pressure difference between the exhaust gas pressure and the depression in said induction pipe or manifold, the injectors being fed with fuel under pressure from a fuel supply through a common supply line and including a return line to the fuel supply fed through a pressure control valve which determines the fuel pressure in said supply line, wherein the pressure control valve is also subjected to a reference pressure which is the same as the pressure of the exhaust gas fed to the injectors, whereby the reference pressure acts on the pressure control valve to alter the pressure of the fuel supply to the injectors in such a way as to provide compensation for variations in fuel flow arising from changes in the pressure of the exhaust gas supply. 